Printing on metal



Patented July 6, 1937 UNITED STATES PRINTING 0N METAL Everard Tuxford Digby, London, England No Drawing. Application January 5, 1934, Serial No. 705,459. In Great Britain January 1'7,

2 Claims.

This invention resides in the production by the processes hereinafter described and pointed out in the claiming clauses concluding this specification and for the purpose of providing imperishable records, of a sheet of incorrodible metal of the thickness of paper whereon there is printed letterpress of platinum or metal of the platinum group (hereinafter, for convenience of reference, designated platinum) such letterpress not depending on bas-relief, relief, plastic recessed, or deep-etched effect for its visibility and being applied as thinly as requirements permit.

According to one example of carrying out my invention, a sheet of, say, gold alloy or nickel is taken and an imprint-say of a page of type or a half tone blockis imposed on it by any convenient photo-transfer, lithographic or other method, and the sheet is treated in a plating bath of copper or other suitable metal so that a metallic masking is electrolytically deposited upon the exposed portion or portions of the sheet, after which the letterpress mask is removed by any suitable known chemical treatment, or otherwise, so as to leave the gold or nickel surface underneath it exposed. It is obvious that by the expression fother suitable metal is meant any metal which will be dissolved by the acid treatment hereinafter referred to. The sheet is now treated in a platinum plating bath when platinum is caused to be electrolytically deposited on both the exposed and metal masked portions thereof. The sheet is then treated by acid to dissolve said metallic masking and to free the platinum coating above it, which latter is in a broken condition and may therefore be readily removed to leave the gold or nickel sheet beneath it free of deposit, whilst the platinum deposited on the gold or nickel remains firmly adherent thereto. It is to be understood that the deposited layer of platinum is sufiiciently thin to permit the acid to dissolve the masking metal beneath the platinum layer. The sheet is now in its finished condition as a gold or nickel base or surface bearing the letterpress in platinum.

According to another example of carrying out my invention, the printing is effected substantially according to the first example, but varies in that the metallic mask is deposited with a strongly matt surface and. is not removed, with the result that the final metal coating is matt over the metallic mask and polished over the exposed portion or portions of the sheet.

According to a third example of carrying out my invention, there is deposited electrolytically over the whole surface of a gold alloy or nickel sheet, a layer of copper or other suitable metal on which the letterpress is imposed by phototransfer, lithography, or otherwise: then the unmasked portion or portions of said layer is etched down to the gold or nickel level by treating the sheet in a bath of any suitable etching liquid, after which the sheet is treated in a patinum plating bath and the process is completed as in the first example.

If desired, the whole of the exposed and masked portions of the sheet may be sand-blasted or otherwise suitably treated prior to the deposition thereon of the final metal, so that the exposed portion or portions of the surface will become matt and said final metal coating will similarly become matt: or the surface of the sheet may be first sand-blasted or otherwise suitably treated so that at the final stage of the process both the sheet and the final metal coating will be matt: or, after treatment of the sheet to obtain a matt surface, the metallic mask in example number two may be deposited with a polished surface; the final metal coating will then be polished on the metallic mask and matt on the exposed sheet.

It is, of course, to be understood that the masks employed may cover the background, or, alternatively, the letterpress itself.

What I now claim as my invention and desire to secure by Letters Patent is:-

1. A process of printing on a non-corrodible sheet metal base, which comprises forming a mask design upon said sheet metal, then depositing a metal on the exposed portions of said base, said deposited metal being soluble in the common mineral acids, then removing the mask, then plating the entire surface of said base with a thin film of a metal chosen from the platinum group of metals, then treating said plated surface with an acid to dissolve the acid soluble metal and remove that portion of the platinum layer which rests thereupon.

2. The process of printing on a gold surface sheet metal base. which comprises forming a mask design upon said sheet, then depositing copper on the exposed portions of said gold surface sheet metal base, then removing the mask, then plating the entire surface of said base with a thin film of a metal chosen from the platinum group of metals, then treating said plated surface with an acid to dissolve the copper and remove that portion of the platinum layer which rests thereupon.

EVERARD TUXFORD DIGBY., V 

